2 . A study of almost 2,700 children aged between seven and ten in 38 schools in Barcelona, Spain, first researches the impact of traffic noise on child cognitive development over time.

The children in the study are in a critical stage for the development of memory and attention skills, which are essential to learning. The research found that children exposed to about three times more traffic in the street than other children had memory development that was 23% slower and attention ability development 5% slower over a year.

Noise is the second most damaging environmental factor to health, after air pollution, and, for example, was already known to increase heart attacks in adults. The UN said that urban noise pollution was growing into a global public health threat, leading to 12,000 early deaths a year in the EU alone and affecting many cities.

But research on the impact of road noise on children was limited until now. “We do not understand that noise can actually be toxic (有害的) from a physical point of view,” said Dr. Maria Foraster, from the Barcelona Institute for Global Health, who led the study. “We think that we adapt to it, but research has shown that we don’t completely — we still have a physiological (生理的) response.”

The research revealed that peaks of noise heard inside the classroom, such as the passing of loud trucks, had more impact than a higher average level of noise. It also found higher noise levels at school were more damaging than at home.

Prof. Iroise Dumontheil, at Birkbeck, University of London, UK, said, “This carefully designed study provides convincing evidence. Considering that many European children living in large cities are exposed to high road-traffic noise levels, this study has implications for public policy to reduce road-traffic noise near schools.”

The research follows previous work that showed higher levels of aircraft noise at school affected reading comprehension and cognitive development. Next, the authors said, they would like to see their findings replicated (复制) in different cities and towns, where schools may be built differently and windows opened more or less often.

4 . Researchers out of Australia’s Flinders University recently studied various physical reactions during sleep when exposed to noise. They found that certain levels of noise exposure while sleeping, even those below recommended safe levels, may affect a person’s cardiovascular (心血管的) response. When slowly activated during sleep, these responses “could potentially have adverse effects on the cardiovascular system,” said researchers.

Researchers exposed 20 adult participants to various decibels (分贝) of wind farm and road noise while asleep, and then monitored physical responses including blood flow and heart rates as well as sleep awakenings. Although asleep, participants reacted to these noises, as found by the researchers.

For example, a 48-decibel (dB) noise, which is quieter than the 50-dB hum of a refrigerator, was 3.4 times more likely to cause a change in participants’ pulse wave amplitude (脉搏波振幅), which is a measurement that relates to blood flow. Participants’ heart rates responded to the noise as well. After being exposed to a noise of over 40 dB, they experienced an increase followed by a decrease in their heart rates. The study noted that these sound levels are under the recommended 70 dB limit by the World Health Organization.

Physiological reactions that the study monitored, such as heart rates and blood flow, may root in the proper responses that may be “potentially needed to defend against threats during sleep,” researchers said.

Sleep is typically a time for the body to rest and recover, and noise-caused activation of these cardiovascular responses during sleep may prevent a person from getting the proper amount of healthy sleep they need.

Researchers noted that exposure to noise pollution during sleep may increase the risk of cardiovascular disease, such as hypertension, heart disease, and other harmful health effects. To help reduce the potential increased health risks caused by frequent noise-caused sleep disturbances, researchers note that their findings help create public policies around noise levels during sleep.

In a study conducted twelve years ago near natural gas wells in New Mexico, researchers found that there were 75% fewer pinon pine seedlings(幼苗) in noisy sites than in quiet     1     . This was most likely due to the noise driving away the scrub jay(灌丛鸦), which plants thousands of pine seeds while     2    (store) them to eat during the winter months. A research team from California Institute of Technology recently returned to the sites to find out whether the pinon pine had recovered     3     time.

    4     companies changed the sites where they used noisy compressors(压缩机) to help produce natural gas, some of the     5    (previous) noisy sites had become quiet. The researchers found that in these areas, there were still fewer seedlings     6    (compare) to sites that didn’t have compressors added to speed up gas extraction. This shows that though the noise was removed before the pinon pine seeds     7    (plant), they still didn’t sprout(发芽).

“The effects of human noise pollution     8    (grow) into the structure of the woodland communities at present,” said biology professor and senior author Clint Francis.     9     we’re seeing now is that     10    (disappear) of the noise doesn’t necessarily immediately result in a recovery of ecological function.

9 . The tradition of giving gifts didn’t start with the modern holidays we celebrate. Many ancient cultures celebrated holidays with the exchange of gifts. People who love to give gifts often can’t wait until it’s time for the recipients to open their gifts. If you’ve ever been given a gift, you know that part of the fun is the curiosity that builds as you wonder what the gift is.

The wish to hide the identity of a gift until just the right moment led people to wrap gifts long, long ago. Historians believed wrapping gifts in paper probably started not long after paper was invented thousands of years ago.

Wrapping paper like what we use today, though, is a much more recent invention. More than 100 years ago, gifts were usually wrapped in heavy brown paper. Before that, cloth was often used. The technology to mass-produce wrapping paper didn’t come along until the early 1900s. The first American gift wrap company— Hy-Sill Manufacturing Inc. — was founded by Eli Hyman and Morris Silverman in 1903. It wasn’t as easy to wrap presents back then as it is today, though, because adhesive tape (胶带) wasn’t invented until 1930.

Over the years, wrapping paper has developed into what we see in stores each holiday season. But scientists say that the United States alone produces an extra 5 million tons of waste over the holidays, most of which is from wrapping paper and shopping bags. To cut down on this waste, some people carefully unwrap presents, so that the wrapping paper can be reused. Others have started to use reusable gift bags instead of wrapping paper.